The reasonable line is that Google wants to get much, much better at speech-to-text, and at understanding what people really want when they say things out loud. By having all your friends leave their voicemails on your Google Voice account, then clicking to mark them as useful or not, and then further sending the message to Google if was a really bad miss, Google will get better at understanding all the ways that humans say things. They already did it with GOOG-411, the free phone directory service that mined voices across the country to launch Google Voice’s current transcription offering.
The stakes are pretty high already, as Google already sees Apple’s Siri assistant as a threat to its core business. Siri obfuscates the source of its answers, which can often be Google, and doesn’t read advertising out loud to you. More than anything, though, Siri is successfully marketed as a place you turn to for answers, while Google has always sought to be the leader in organizing the world’s information and making it accessible. Google is reportedly looking to launch its own assistant in late 2012, and one has to assume that Voice functions will play an integral role in that assistance.